Just got a '75 Carpenter RE bus with a Ford 534, Allison automatic, and (why do I do this?) it has been running on strictly propane all it's life. Seems to have adequate power - nothing stellar, and just over 3000 rpm indicated gives a comfy 55 mph cruise - 3200 is about 60 mph.

I see the specs are 277 hp at 3200 rpm, and 480 ft/lbs torque. I wonder which model Allison tranny I have?

So, distilling the web research, it is 277 hp @3200 rpm, 480 ft/lbs of torque around 1800 to 2200 rpm, and 2 to 3 mpg. I can add that running under propane fuel (it was propane since birth - The bus is a '75 and that was around the other "oil crisis" and gas rationing times) from Seattle to Spokane between 55 and 60 mph, I burned 131 gallons of propane, or 2.68 mpg, in a 35 foot Carpenter RE bus with an automatic tranny. It would have gone faster (it would jump up to the middle 60's if I did not pay attention and left my boot on the pedal) but I thought that might not be "wise". Hey, it is for a mostly stationary bus with occasional "oh crud, lets bug out ahead of ___fill in your disaster here___" capabilities.

4.5 bore by 4.2 stroke....practically speaking it redlines around 4000 RPM....~260 hp at 3200 RPM and ~480 ft lbs@1700 RPM. They are big, tough motors, but lack interchangability with much of anything else other than maybe an even older 477. They can be difficult and expensive to get parts for, but are supposedly pretty tough like any other industrial gas engine as long as you aren't flogging on them too hard.

I noticed there is not a HUGE overhang of the back.... probably not a bad idea to keep the front end down. But I was not surprised by huge amounts of power.... basically it had just the right amount of power to get the job done, and was not a pain in the butt to drive around, and it would keep up to 40 mph in the passes (driving empty).

I keep wondering if I took my 454 out of the old pickup, a little hot rodding, and then dropped it in. While the HP of the stock 454 is similar (270 hp vs 277 on the 534) the stock torque of the BBC motor is 360 ft/lbs... not the 480 of the big Ford motor. Of course, I see built up BBC 454 engines rated at 450 hp and 500 ft/lbs of torque......

Hmmmm - maybe I will just save my money and keep my eyes out for a DT466 equipped bus coming up surplus at the school district, instead.... or save my money and just not take long trips!